Production of acenaphthylene



Patented June 11, 1935 UNITED. STATES 2,004,884 PATENT OFFICE 2,004,884 PRODUCTION OF ACENAPHTHYLIi'INE No Drawing. Application November 3, 1933,

Serial No. 696,536.

4 Claims.

The present invention relates to a process for the manufacture of acenaphthylene.

We have found that acenaphthylene can be obtained in quantitative yields by passing vapours of acenaphthene at temperatures between about 500 and about 850 0., preferably between about 600 and about 750 C., over dehydrogenation catalysts which are solid and not reducible to metals by hydrogen at the working temperatures. The said catalysts will accordingly be called solid dehydrogenation catalysts which are not reducible to metals under the working conditions.

The said dehydrogenation catalysts comprise compounds of solid, heavy metals which are solid and not reducible to metals by hydrogen at the working temperatures, such as compounds of zinc, chromium, molybdenum, tungsten, uranium and manganese. The said compounds comprise for example oxides and sulphides of said metals, as well as sulpho-oxides and also solid salts in which said metals form part of the acidic component, such as is the case in the so-called metal acids and the corresponding sulpho-metal acids in which the oxygen atoms of the metal acids are partly or completely replaced by sulphur atoms.

It will be understood that compounds of heavy metals, such as gold, silver, platinum, iron, cobalt and nickel, which are readily reducible by hydrogen at the said working temperatures are not dehydrogenation catalysts according to the above definition. Similarly compounds of alkaliand alkaline earth metals, including aluminium and magnesium, are not dehydrogenation catalysts according to the above definition, since these metals are not heavy metals. On the other hand, however, the metals the compounds of which are not, per se, among the dehydrogenation catalysts according to the above definition, may form part of the said catalysts, as basic components of the aforesaid metal acids and sulph-o-metal acids.

Specific examples of solid compounds suitable as catalysts are oxides and sulphides of zinc, chromium, molybdenum, tungsten, uranium and manganese, and chromates, chromites, molybdates, tungstates, uranates and manganites, and the corresponding sulpho-molybdates, sulphotungstates and like sulpho-salts of, for example, alkaline earth metals, such as calcium, strontium, barium, magnesium and beryllium (these metals belonging to the even series of the alkaline earths: see Partington, Text-Book of Inorganic Chemistry, 1931, page 817) of metals of the rare earths (i. e. metals having an atomic number between 57 and '71), such as lanthanum, cerium, praseodymium, neodymium, illinium, samarium, europium, gadolinium, terbium, dysprosium,- holmium, erbium, thulium, ytterbium and lutecium, and metals of the odd series of the 4th group (see Partington, etc., page 893), such as titanium, zir- In Germany July 22, 1932 conium, hafnium and thorium. The said chromates, chromites, molybdates, tungstates, uranates and manganites, and the corresponding sulpho-molybdates, sulpho-tungstates and like sulpho-salts also comprise those of zinc and aluminium.

Similarly mixtures of the said compounds of solid, heavy metals which are solid and not reducible to metals by hydrogen at the working temperatures with compounds of light and/or reducible solid metals may be employed, provided these compoundsare not fusible at the working temperatures. Additional compounds of this kind are for example the oxides, carbonates,

sulphates, sulphides and phosphates of the aforesaid metals belonging to the even series of the alkaline earths and the oxides, carbonates, sulphates, sulphides and phosphates of the aforesaid metals of the rare earths and of aluminium. Small amounts of alkali metal compounds (Na, K, Li) may also be present in the catalysts as accelerators. Usually alkali metal carbonates, nitrates or nitrites, or like decomposable compounds are incorporated with the catalyst during its preparation, the catalyst being then heated and the carbonates or nitrates decomposed. It is sometimes advantageous to employ the said catalysts precipitated 'on solid carriers having a large inner surface, such as active carbon, bleaching earths. The efficiency of these catalysts may still be increased by a thermic pretreatment by means of hydrogen or gases or vapours giving off hydrogen or sulphur, such as ammonia or sulphuretted hydrogen or carbon. This pretreatment may be carried out at a temperature of, say, 300 C. which slowly increases up to, say, 600 C.

The said solid dehydrogenation catalysts which are not reducible to metals under the working conditions also comprise silicon and carbon in the elemental state, that is to say crystalline silicon and lustrous carbon.

Crystalline silicon is usually employed in the form of pieces which are filled into the reaction vessel or tube whereas lustrous carbon is generally employed as a coating on a solid carrier. Thus, for example, copper may be coated with lustrous carbon by a treatment at red heat with carbon containing gases or vapors, such as ethylene or gasoline. The copper is in this case preferably used as a thin inner coating of tubes made from heat-resistant alloys, such as chromium nickel alloys or chromium nickel steel alloys or nickel steel alloys. The lustrous carbon may also serve to coat carriers made from those compounds of light metals which are not reducible and fusible under the Working conditions and are not, per se, dehydrogenation catalysts according to the above definition, but may be used as additions to said catalysts. For example,

lustrous carbon may be deposited on oxides, carkali metals, for example potassium pyrophosphate, alumina, aluminium, pyrophosphate, silicic materials, such as porcelain, quartz, feldspar, clay, silicium carbide, boron nitride, calcium carbide (in which case no steam may be employed in the recation) and other solid materials, such as graphite. 1

Elemental silicon may likewise be employed on solid carriers by burning in powdered crystalline silicon.

The reaction is preferably carried out at a pressure up to atmospheric pressure, that is to say in vacuo or at atmospheric pressure. The employment of a pressure below atmospheric pressure is advantageous, because it facilitates the reaction which proceeds with increase of the volume, and prevents splitting and condensations; simultaneously the life of the catalyst is prolonged.

The vapors of acenaphthene may be diluted with inert gases or vapors, such as nitrogen, hydrogen, carbon dioxide, methane or steam, which dilution acts similarly as the employment of a reduced pressure. Usually, 1 part by volume of vapors of acenaphthene is diluted with from about 1 to about 100 parts by volume of the said diluents which, for the sake of brevity, will be called inert gaseous diluents, since they do not chemically react with the initial or final vapors. When working under reduced pressure a small dilution within the said range is employed. a

' The reaction vessel is usually formed by tubes made from heat-resistant alloys, such as V2A steel (containing 72% of iron, 7% of nickel and 19.6% of chromium), chromium steels, chromium nickel steels or chromium nickel alloys. It is possible to coat the inner surface of the tubes with a layer of another metal by decomposing therein volatile metal compounds, such as chromyl chloride, molybdenum carbonyl and the like.

The following examples will further illustrate the nature of this invention, but the invention is not restricted to these examples.

Example 1 A mixture of the vapors from 1.2 kilograms of acenaphthene with 4 cubic metres of nitrogen is passed in the course of 24 hours over each litre of a catalyst which is heated at between 580 and 600 C., and consists of a mixture of zinc molybdate-with an equimolecular proportion of magnesia. A quantitative yield of yellow acenaphthylene, having a melting point of 91 C., is obtained.

Example 2 diluent.

verted, the yield of pure acenaphthylene being about 90 per cent Similar results are obtained while employing carbon dioxide instead of nitrogen as gaseous The reaction may also be carried out under reduced pressure of say 0.1 atmosphere.

Example 3 A mixture of the vapors of 1.25 kilograms of acenaphthene and 6.25 kilograms of water is passed in the course of 24 hours at between 760 and780 C over each litre of the catalyst described in cxample 2. The acenaphthene is practically quantitatively converted, the yield of acenaphthylene being about 90 per cent. Although the reaction temperature is extremely high no formation of water gas occurs.

If, instead of the nickel chrome tubes containing magnesia coated with lustrous carbon as a. catalyst, only quartz tubes are employed as the reaction vessel without using catalysts, only from 40 to 50 per cent of acenaphthene are converted under the said conditions. Moreover, the acenaphthylene can only be obtained in a pure form after repeated crystallizations of the reaction product.

Example 4 A mixture of the vapors of 1.25 kilograms of acenaphthene and 6.25 kilograms of water is passed in the course of 24 hours at between 760 and 780 C. over each litre of crystalline silicon, arranged in the form of small pieces in a tube made from V2A steel (containing 72% of iron,

7% of nickel and 19.6% of chromium) provided with a thin inner coating of molybdenum, prepared by heating the empty tube and leading therethrough a current of molybdenum carbonyl. The acenaphthene is practically quantitatively converted into acenaphthylene.

What we claim is:-

1. The process for the production of acenaphthylene which comprises passing vapors of acenaphthene at between about 550 and about 850 C. over a solid dehydrogenation catalyst selected from the group consisting of carbon and silicon in the elemental state at a pressure up to atmospheric pressure. a

2. The process for the production of acenaphthylene which comprises passing vapors-of acenaphthene together with an inert gaseous diluent at between about 550 and about 850 C. over a solid dehydrogenation catalyst selected from the group consisting of carbon and silicon in the elemental state. I

3. The process for the production 01' acenaphthylene which comprises passing vapors of acenaphthene together with an inert gaseous diluent at between about 550 and about 850 C; over a solid dehydrogenation catalyst selected from the group consisting of carbon and silicon in the elemental state at a pressure up to atmospheric pressure.

4. The process for the production of acenaphthylene which comprises passing vapors of acenaphthene at between about 550 and about 850 C. over a solid dehydrogenation catalyst selected from the group consisting of carbon and sili-' con in the elemental state.

CARL WULFF. OTTO NICODEMIUS. MAX TREPPENHAUER. 

